Advances in electronic technology have enabled various types of data signals to be transmitted through standard telephone transmission lines. An example of such a non-standard data signal transmitted across telephone lines is a telecopier, or facsimile, signal (also commonly referred to as a "fax"). Transmission of non-standard data signals across standard telephone communications equipment has often created problems in that standard telephone communication equipment is not generally designed to handle some types of data signals. One of the problems created is that the amplitude of some transmitted data signals is too great for successful data transmission. Thus, it can be appreciated that it would be useful to have a means for attenuating non-standard data signals which are transmitted through a standard telephone communications system. Since not all telephone subscribers transmit and receive data signals, it can be further appreciated that it would be useful to have a means for attenuating non-standard data signals in a standard telephone communications system which means is easily insertable at the customer interface.